Homomorph

English has many pairs of words which are spelt and pronounced in the same way, share the same etymology and have closely related meanings, but differ in belonging to different word classes. For example, ‘rest’ may be either a noun (as in ‘We’ve worked hard, let’s have a rest’) or a verb (as in ‘You’ve been very ill: you need to rest’); ‘red’ may be either an adjective (as in ‘I prefer the red tie’) or a noun (as in ‘The red in that tie is much too bright’); and ‘inside’ may be either an adverb (as in ‘It’s turned cold; let’s go inside’) or a preposition (as in ‘Inside the box there were some old photographs’). (For more on ‘inside’ see further below.)

Words which satisfy all the above conditions, i.e., are identical in spelling and pronunciation, are closely related in meaning, but belong in different word classes, are sometimes known as homomorphs – a term proposed in R. Quirk, S. Greenbaum, G. Leech, and J. Svartvik, A comprehensive grammar of the English language (Longman, London and New York, 1985), and listed in Bas Aarts, Sylvia Chalker, and Edmund Weiner, The Oxford Dictionary of English Grammar (2nd edition, OUP, 2014), p. 196. The word homomorph, which has a well-established use in biology to refer to a part of a plant or animal which is similar in form to another part, derives from the Greek ὁμός (homos, ‘same’, ‘common’, ‘joint’) and μσρφή (morphe, ‘form’, ‘shape’). There is a related adjective, homomorphic, and related nouns homomorphy and homomorphism.

Note that the close connection of meaning (and shared etymology) is essential – it is what distinguishes homomorphs from homonyms, words which look and sound identical but have distinct, unrelated meanings.

Here are a few more examples of homomorphs:

dry, which is a verb in ‘They dry the leaves by leaving them in the sun’ and an adjective in ‘When the leaves are dry, they grind them to a fine powder’;

visit, which is a verb in ‘They visit their aunt every year’ and a noun in ‘Their visit yesterday came as a surprise’;

behind, which is an adverb in ‘We left him behind’ and a preposition in ‘I found the ring behind the settee’;

votes, which is a verb in ‘He always votes in local elections’ and a noun in. ‘They will count the votes in the morning’;

return, which is a verb in ‘They return from their holiday tomorrow’ and a noun in ‘We eagerly await their return’..

A final thought: Since stress is an element in pronunciation, two words which are identical in pronunciation apart from having the stress on different syllables should perhaps not be considered to be homomorphs. So 'inside’ as a noun, as in ‘The inside of the box was lined with silk’, with the stress equally distributed between the two syllables, and 'inside' as an adjective, as in ‘The police think it is an inside job’, with the stress on the first syllable, are not homomorphs – either with each other or with ‘inside’ as an adverb or a preposition, when the stress is on the second syllable (see above).

See also Homonym, Homophone,Homograph, and Word class confusion..